High prevalence of undiagnosed COPD among patients evaluated for suspected myocardial ischaemia

OBJECTIVE: Chronic obstructive pulmonary disease (COPD) and coronary artery disease (CAD) are leading causes of global morbidity and mortality. Despite the well-known comorbidity between COPD and CAD, the presence of COPD may be overlooked in patients undergoing coronary evaluation. We aimed to assess the prevalence of undiagnosed COPD among outpatients evaluated due to suspected myocardial ischemia. METHODS: Among 500 outpatients who were referred to myocardial perfusion imaging due to suspected stable myocardial ischaemia, 433 patients performed spirometry. Of these, a total of 400 subjects (age 66 years; 45% women) had no previous COPD diagnosis and were included in the current study. We compared the prevalence of previously undiagnosed COPD according to spirometry criteria from The Global Initiative for Chronic Obstructive Lung Disease (GOLD) or lower limit of normal (LLN) and reversible myocardial ischaemia according to symptoms and clinical factors. RESULTS: A total of 134 (GOLD criteria; 33.5 %) or 46 patients (LLN criteria; 11.5%) had previously undiagnosed COPD, whereas 55 patients (13.8 %) had reversible myocardial ischaemia. The presenting symptoms (chest discomfort, dyspnoea) did not differ between COPD, myocardial ischaemia and normal findings. Except for smoking, no clinical factors were consistently associated with previously undiagnosed COPD. CONCLUSIONS: Among middle-aged outpatients evaluated due to suspected myocardial ischaemia, previously undiagnosed COPD is at least as common as reversible myocardial ischaemia and the presenting symptoms do not differentiate between these entities. Patients going through a coronary ischaemia evaluation should be additionally tested for COPD, especially if there is a positive history of smoking.